It is known in the art of electroplating to use frames on which are removably anchored plates or the like articles to be plated, for holding them while they are being submerged in large acid tanks or baths, e.g. for creating printed circuit boards.
In applicant's U.S. Pat. No. 5,904,820 issued May 18, 1999, there was disclosed and claimed a holding clamp for releasably holding an article to be submerged in a liquid solution bath ahead of a submerged anode bar and to be electroplated therein. This patented holding clamp, destined to downwardly depend from an overlying cathode frame bar, comprises a first and a second elongated arm members made of an electrically conducting material and each defining a lower portion coated with a fluid-tight and electrically insulating sleeve, and an upper and a lower end, the first arm member to be fixedly attached to the cathode frame bar at its upper end, the second arm member being shorter than the first arm member and being pivotally attached to the first arm member and being pivotable between a first limit position in which the lower ends are spaced from one another and a second limit position in which the lower ends abut against one another, the first arm member having electrical current conduction means physically accessible at its lower end. Biasing means biases the arm members lower ends against one another, and a lever member pivotally attached to an intermediate section of the first arm member and located entirely above the first and second arm member sleeves at all times selectively forcibly pivotally biases the second arm member into the first limit position against the action of the biasing means. In this way, the first and second arm members are destined to frictionally hold the article to be electroplated between their lower ends when the second arm member is in its second limit position, thus allowing current to be conducted through the conduction means into the article, with the first and second arm member lower portions destined to be submerged in the solution at the most partially up their sleeves.
Such a holding clamp device is very efficient for holding thin single layer planar articles. However, recent technical developments in the printed circuit boards have brought about thicker, multiple layer printed boards. Because of their greater overall thickness, the jaw studs of the prior art holding clamps are much more spread apart than before. Since the relative movement between the two jaws is a pivotal one about a circle of an arc, when the jaws are opened from their closed condition, the jaws do not remain parallel to one another and accordingly, the studs become eventually axially offset relative to one another. This means that electrical conduction between the studs from the two opposite jaws from a given clamp, becomes compromised in a progressively increasing fashion as the jaws are progressively pivoted away from one another.